1. Non-Mendelian Genetics

2. It’s Complicated Many traits do not follow Mendel’s simple dominant/recessive rules Polygenic Trait: trait can be influenced by several genes Genes may be on the same or different chromosomes Incomplete Dominance: phenotype displays a trait that is a blend of the two parents Multiple Alleles: gene has three or more versions Ex: Blood Type Codominance: two dominant alleles are expressed at the same time Sex-linked traits Environmental Factors

3. Polygenic trait Two or more genes effect the phenotype Ex: Eye color, height, weight, skin color

4. Incomplete Dominance Offspring’s phenotype is a blend of the parental phenotypes. Notation: all alleles are written as capital letters, however a different letter is used to represent the different alleles Ex: Red (RR), White (WW) parents would make Pink (RW) offspring RR WRW W

5. Multiple Alleles Genes has three or more alleles Ex: Human blood has three alleles I A, I B, and i Produces 4 blood types, A, B, AB, and O The A, B alleles control the production of a specific sugar on red blood cells The i allele causes the cell to produce no sugar on the surface

6. Multiple Alleles

7. Codominance Two dominant alleles are expressed at the same time Typically produces a spotted appearance Ex: AB blood type – Both the A and B sugar is present on the surface of a red blood cell Spotted Flowers FBFB FBFB FWFW FBFWFBFW FBFWFBFW FWFW FBFWFBFW FBFWFBFW

8. Sex-linked traits Trait whose allele is located on the sex chromosome Most are on the X chromosome Typically, will only see the recessive allele in males Females that are heterozygous are considered “carriers” Most negative sex-linked traits are recessive Y Linked traits typically are not passed on because they cause sterility Ex: Color Blindness, Hemophilia

9. Sex-linked traits XBXB Y XBXB XBXBXBXB XBYXBY XbXb XBXbXBXb XbYXbY

10. Environmental Factors Can change the phenotype of an organism Typically is based on factors such as temperature, radiation, or acidity Ex Human Skin Color Certain flowers’ color Arctic Fox Coat (white in winter, brown is summer)